SPONTANEOUS COMBUSTION.

Te Aroha News, Volume VII, Issue 410, 12 October 1889, Page 4

SPONTANEOUS COMBUSTION.

Auckland, October 8. The following is the subsfcanceof Mr Pond's lecture on the above subject, delivered in the V.M.C.A. Rooms on Friday night. The lecturer opened by saying that spontaneous combustion was better known by name than by actual experience. Combustion is best defined as a chemical union causing heat and perhaps giving forth lierht. All bodies contain potential heat. The process of decuy i? a species of clow combustion, as Liebig says. But the combustion of putrefaction and fermentation are much different from the rapid combustion ot a tire. The more a body is divided the more rapidly combustion takes place ; so that it the body be reduced to powder there occurs an explosive combustion of the class that has sometimes wrecked flourmills or other buildings. The reason is that a much larger surface is thus exposed to oxygen. Many deny altogether that spontaneous combustion can take place, and of couise if the inquiries into any combustion be earned out fully some actual cause must be found. Besides tine division a bad conducting power is needed for spontaneous combustion. It is well known that tires otten occur in coal mines without any appaient cause, but these fires aie always caused by chemical combination. The oxygen being allowed into the finely divided coal dust cau&es slow combustion. This causes heat, and the heat tiies the explosive ga-es piesent. Tho lecturer explained this portion of his address by the old experiment with potassium and water. Another experiment was shown with tartrate of lead, which was heated, and tho lead remaining in fine division buined in the oxygen of the air. The process of decay of matter was explained. At first the hydrogen ot the body unites with the oxygen of the air, then with the carbon ; and as this goes on an increase of heat takes place perhaps, ending as often in the case of hayricks, in incandescence and fire. The effects of these facts on the making of encilage were then explained. In animal matter ammonia is formed, and being inimical to lire this ammonia prevents substances which may be \ery hot fiom breaking into flame. This is the reason that wool, though it may get almost red hot, ha? never in our vessels broken into tlame. All fibrous materials placed in oils that gi\e otl oxygen easily, soon gain a great deal of heat and will burst into flame if the heat rise to 800deg. Hence oils in cotton mills must Lie veiy carefully chosen. In a speech some time ago Mr Farquhar, of Vic oria, stated that New Zealand flax had an evil reputation for spontaneous combustion, probably owing to the presence of some resinous matter. The lecturer said that spontaneous combustion might take place from this matter being present, but of such matter there was not more than one per cent, altogether in green flax, and that was got rid of in the process of manufacture, as it was all on the surface of the blade. Moreover, there was no instance of incandescence that he knew of from spontaneous combustion of flax. There had been talk of various expeiiments to piove whether such spontaneous combustion might take place, but su^h experiments could not easily be cariied out in the way proposed. Moreover, they were practically being carried out in all our mills, ships, storehouses, etc., throughout the country wherever flax was kept. It was mainly this statement of Mr Farquhar's that led him to take up this subject, for he was very jealous of the reputation of all New Zealand products, and he was anxious to correct all mis-statements about them. Though spontaneous combustion was generally harmful, yet it could at times be made very useful, as in the case of lifesaving apparatus for men-of-war. If a man tell ovei board an object was thrown after him which gave a light on falling into the water for about twenty minutes, guiding the lifeboat to the man and the man to the lifeboat. An interesting explanation was given of what are known as " singing flames." Further experiments were shown explaining how combustion takes place with or without oxygen. Anotherimoortant inquiry was how combustion might be prevented. The best way was by the use of chemical salts, which prevented flame and [ could be used with any material, so that the flame could be kept easily under control. Unfortunately, people never bothered to use these substances, and insurance companies made no effort to encourage their use. Seeing that science had proved the value of such salts, it was a cruel wrong that they were not used in asylums, hospitals, and other public buildings. Private people might be foolish enough to keep up the premiums and dividends of insurance companies, but there was no excuse for public bodies An experiment was shown with saturated paper, demonstrating the value of these flame killing salts. A hearty vote of thanks to the lecturer concluded the proceedings.